Messages in this thread Patch in this message | | | From | Michael R Sweet <> | Subject | [PATCH] Fix default q_len for usb_f_printer gadget driver | Date | Mon, 28 Dec 2020 12:18:24 -0500 |
| |
The usb_f_printer gadget driver uses a default q_len value of *0* which prevents any IO from occurring. Moreover, once the driver is instantiated it is impossible to change the q_len value.
The following patch uses a default q_len value of 10 which matches the legacy g_printer gadget driver. This minimizes the possibility that you end up with a non-working printer gadget. It is still possible to set the q_len to a different value using the configfs path of the same name.
Signed-off-by: Michael R Sweet <msweet@msweet.org> --- drivers/usb/gadget/function/f_printer.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/drivers/usb/gadget/function/f_printer.c b/drivers/usb/gadget/function/f_printer.c index 9c7ed2539ff7..4f3161005e4f 100644 --- a/drivers/usb/gadget/function/f_printer.c +++ b/drivers/usb/gadget/function/f_printer.c @@ -50,6 +50,8 @@ #define GET_PORT_STATUS 1 #define SOFT_RESET 2
+#define DEFAULT_Q_LEN 10 /* same as legacy g_printer gadget */ + static int major, minors; static struct class *usb_gadget_class; static DEFINE_IDA(printer_ida); @@ -1317,6 +1319,9 @@ static struct usb_function_instance *gprinter_alloc_inst(void) opts->func_inst.free_func_inst = gprinter_free_inst; ret = &opts->func_inst;
+ /* Make sure q_len is initialized, otherwise the bound device can't support read/write! */ + opts->q_len = DEFAULT_Q_LEN; + mutex_lock(&printer_ida_lock);
if (ida_is_empty(&printer_ida)) { -- 2.17.1
| |